The results of CO2 spectral lines shifts measurements made in air and pure CO2 gas for some lines in the 1.4, 2.7, 4.3, 4.8, 9.4 and 10.6 m bands are presented in the paper. Obtained values of shift coefficient lie in the range from 0 to ±0.025 cm-1•atm-1. The influence of the collisional shifts on the propagation of CO2 laser radiation throught the atmosphere is estimated. It is shown that lineshift can cause the increase of monochromatic transmission of vertical atmospheric column almost twice for some laser frequencies.